[clug] KVM and PCI pass-through

[Scott Ferguson]

On 03/06/15 09:35, Bob Edwards wrote:
> Anyone on list had any experience with PCI pass-through in KVM?
> 
> We have had some partial success in getting an old PCI DAQ card
> "passed-through" to an ancient copy of Windows 2000 running as a
> KVM guest on a Debian Jessie host. There were issues with shared
> interrupts causing some problems which we were able to resolve,
> but we still have some issues with reading some memory areas from
> the DAQ card.
> 
> Have also tried it with VirtualBox with less success.
> 
> Next step is to try it with a Linux guest and write some code on
> the guest side to see what we can see.
> 
> Any other tips or warnings?


Yes, and, no. :)
I've little experience with KVM, but some with VirtualBox which I'll put
here in case someone else uses it.

VirtualBox supports PCI-passthrough if:-
;VirtualBox extensions is installed
;the host box has IOMMU hardware support (AMD-Vi, Intel VT-d) *and* it's
enabled in the BIOS, *or* some PCI serial cards *if* host bus mastering
is disabled for the device
;some PCI-Express cards if GART is *not* used
;the guest is configured for nested paging and AMD-V/VT-d
;the host kernel has IOMMU, DMA remapping, and the PCI stub driver
(standard in kernel > 2.6.31) *and* uses the IOMMU modules (grep -i
'dmar\|pci-dma' dmesg) (may also require "intel_iommu=on" boot option)
;the card doesn't share interrupts (support 'can' be flaky when IRQs are
shared)
;you "attach" the device (VBoxManage modifyvm "VM name" --pciattach
blah.0:blah.0)


In your instance it 'should' work if your host hardware supports it, you
may also need to customize the guest BIOS settings. I've done similar
with an old PCI video-processing card in an XP guest.

> 
> cheers,
> 
> Bob Edwards.

Kind regards